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2. Automatic. The water and oil are automatically expelled. These tanks may be equipped for manual draining as well. Automatic air tanks are available with electric heating devices. These help prevent freezing of the automatic drain in cold weather.
Some air brake systems have an alcohol evaporator to put alcohol into the air system. This helps to reduce the risk of in air brake valves and other parts during cold weather. inside the system can make the brakes stop working. Check the alcohol container and fill up as necessary, every during weather. Daily air tank drainage is still needed to get rid of water and oil (unless the system has automatic drain valves).
A safety relief valve is installed in the first the air compressor pumps air to. The safety valve protects the and the rest of the system from too much pressure. The valve is usually set to open at psi. If the safety valve air, something is wrong. Have the fault fixed by a mechanic.
You apply the brakes by pushing down the brake pedal (also called the “foot valve” or “treadle valve”). Pushing the pedal down harder applies more pressure. Letting up on the brake pedal reduces the pressure and releases the brakes. Releasing the brakes lets some compressed air go out of the system, so the air pressure in the tanks is reduced. It must be made up by the air compressor. Pressing and releasing the pedal unnecessarily can let air out faster than the compressor can replace it. If the pressure gets too , the brakes will not work.
Foundation brakes are used at each wheel. The most common type is the drum brake. The parts of the brake are discussed below. Brake Drums, Shoes and Linings. Brake drums are located on each end of the vehicle's . The are bolted to the drums. The braking mechanism is inside the drum. To stop, the brake shoes and linings are pushed against the inside of the drum. This causes , which slows the vehicle (and creates heat). The a drum can take without damage depends on how hard and how long the brakes are used. Too much heat can make the brakes stop working. S-cam Brakes. When you push the brake pedal, is let into each brake chamber. Air pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. This turns the S-cam (so called because it is shaped like the letter “S”). The S-cam forces the brake away from one another and presses them against the inside of the brake . When you release the brake pedal, the S-cam rotates back and a spring pulls the brake shoes away from the drum, letting the roll freely again. (See Figure 5.2.) Wedge Brakes. In this type of brake, the brake chamber rod pushes a wedge directly between the ends of two brake . This shoves them apart and against the of the brake drum. Wedge brakes may have a single brake chamber or two brake chambers, pushing in at both ends of the brake shoes. Wedge-type brakes may be self-adjusting or may require manual adjustment. Disc Brakes. In air-operated disc brakes, air pressure acts on a brake and adjuster, like S-cam brakes. But instead of the S-cam, a “power screw” is used. The pressure of the brake chamber on the slack adjuster the power screw. The power screw clamps the disc or rotor between the brake lining pads of a caliper, similar to a large . brakes and brakes are common than S-cam brakes.
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